Implantable medical leads are used in conjunction with electrical medical devices for a variety of purposes, such as delivery of therapy or monitoring of a condition. Implantable medical leads are typically flexible along their length, but are limited in extension by the length of the lead. Due to their limited extensibility, implantable medical leads may be tensioned by movements of the body in which they are implanted. Such tensioning of the lead may cause the lead to limit movement of the patient's body or may cause the lead to migrate or to be pulled from its intended location within the body.
To overcome such problems, extra lead length or slack can be provided to allow for freedom of movement on the part of the patient and little movement of the lead distal portion from or within its intended location. In some cases, loops or coils are introduced in the lead as the lead is being implanted to provide for strain relief. However, as different implanting physicians may form such loops or coils in different manners, the amount and effectiveness of such strain relief may be variable. Further, tissue may adhere to or grow in between extra lead length or slack or loops or coils limiting their effectiveness to provide strain relief.